The present invention relates to a hydrocarbon solvent. More particularly, it relates to a hydrocarbon solvent comprising a fraction, which contains 1-phenyl-1-(p-isopropylphenyl)ethane that is obtained by reacting cumene and styrene, and a pressure-sensitive copying material, which is made with the above solvent.
It has hitherto been well known that the pressure-sensitive copying materials are prepared using various hydrocarbon solvents. For example, a sheet of paper (upper sheet) is applied with microcapsules enclosing a solution of an electron-donating color former (hereinafter referred to as xe2x80x9ccolor formerxe2x80x9d), and another sheet of paper (substrate sheet) is applied with an electron-accepting substance (hereinafter referred to as xe2x80x9ccolor developerxe2x80x9d) such as clay and polymeric materials which can produce colors upon reacting with the above color former. When copying materials are used, the treated surfaces of the above-mentioned set of sheets are put together face to face and pressure is applied to the paired sheets by handwriting or typewriting, thereby obtaining duplicate recordings.
The recording mechanism of this type is such that the microcapsules are ruptured by the pressure of handwriting or the impact of typewriting to release the color former solution. The solution comes into contact with the color developer on the opposite surface of the other sheet of paper to produce a color. In other types of known copying materials, both a lower layer of color developer and an upper layer of microcapsules are applied to a surface of a substrate sheet, or a mixture of microcapsules and a color developer is applied to a substrate sheet.
The color former solution that is used for the copying materials of this kind is a solution of an electron-donating color former in one or more kinds of hydrophobic solvents.
As this type of color former solvent, 1-phenyl-1-(isopropylphenyl)ethane is proposed in Japanese Laid-Open Patent Publication No. 48-92115. The above 1-phenyl-1-(isopropylphenyl)ethane is a satisfactory solvent because it is odorless and be excellent in color-developing property. In addition, it can be produced without difficulty by reacting cumene with styrene as disclosed in the above reference, and it is also favorable in industrial viewpoint because the cumene and styrene as starting materials are inexpensive.
As disclosed in the above publication, 1-phenyl-1-(isopropylphenyl)ethane may include three kinds of isomers, namely, o-, m- and p-isomers, according to the positions of isopropyl groups on the benzene ring. As the result of investigation by the present inventors, it was found out that p-isomer is most excellent in the solvent property for dyestuffs, in addition, it is low in viscosity. Therefore, it is high in color-developing rate, while the other isomers do not necessarily have these desirable properties.
The above-mentioned patent reference describes, with referring to British Patent No. 896864, that 1-phenyl-1-(isopropylphenyl)ethane can be produced easily by reacting cumene and styrene according to this method. However, the conventional catalyst containing acid-treated clay catalyst as proposed in the above British Patent is not always sufficient in the selectivity for producing p-isomer. Therefore, the 1-phenyl-1-(isopropylphenyl)ethane that is described in examples of the above patent is not always satisfactory in the solubility for dyestuffs, the color-developing rate and so forth, and besides, a large quantity of styrene dimers are produced as by-products.
It is also the case with the method described in Japanese Laid-Open Patent Publication No. 48-92114, in which sulfuric acid is used as a catalyst in the reaction of cumene and styrene, or with the method described in Japanese Laid-Open Patent Publication No. 49-31652, in which acid clay is used.
Furthermore, in the production of 1-phenyl-1-(isopropylphenyl)ethane by reacting styrene and cumene as described above, two kinds of styrene dimers are produced as by-products. In addition, these dimers differ from 1-phenyl-1-(isopropylphenyl)ethane in the number of carbon atoms by only one, therefore, the boiling points of them are close to each other. Accordingly, when distillation is employed for the separation in an industrial scale, the dimers are liable to be entrained into the fraction containing 1-phenyl-1-(isopropylphenyl)ethane.
The two kinds of styrene dimers produced as by-products are 1,3-diphenylbutene and 1-methyl-3-phenylindane. Between them, 1-methyl-3-phenylindane, particularly, sometimes produces undesirable effect on the odor of products.
The object of the present invention is to provide a hydrocarbon solvent which is inexpensive and has excellent properties, especially a hydrocarbon solvent consisting of 1-phenyl-1-(p-isopropylphenyl)ethane that is excellent in the dissolving power for dyes and color-developing rate, and is odorless without any problem. Another object of the invention is to provide a pressure-sensitive copying material that is made using the above solvent.
A first aspect of the present invention, therefore, relates to a hydrocarbon solvent characterized in that the solvent comprises a fraction which is produced by reacting styrene and cumene in the presence of an acid catalyst. The fraction contains 85% by weight or more of 1-phenyl-1-(p-isopropylphenyl)ethane and 5% by weight or less of total content of styrene dimers.
A second aspect of the present invention relates to a hydrocarbon solvent as described in the above first aspect, in which the weight ratio of 1,3-diphenylbutene to 1-methyl-3-phenylindane in the styrene dimers is 0.02 or less.
A third aspect of the present invention relates to a pressure-sensitive copying material, which comprises an electron-accepting color developer and a solution of electron-donating color former that is dissolved in a hydrocarbon solvent as described in the above first or second aspect, the color former producing a color when it is brought into contact with the above color developer.
A fourth aspect of the present invention relates to a pressure-sensitive copying material as described in the third aspect, which comprises microcapsules enclosing a solution of electron-donating color former and a sheet-like support carrying there on the microcapsules.
The present solvent contains a large quantity of the p-isomer of 1-phenyl-1-(isopropylphenyl)ethane, so that it is excellent in dissolving power for dyes and color-developing rate. Moreover, because the content of 1,3-diphenylbutene relative to the styrene dimers is small, disagreeable odor is not produced. Furthermore, because 1-phenyl-1-(isopropylphenyl)ethane according to the present invention can be produced without difficulty by reacting cumene with styrene, the obtained solvent is inexpensive.
In the following, the present invention will be described in more detail.
As the 1-phenyl-1-(isopropylphenyl)ethanes, there are three kinds of position isomers, in which isopropyl group occupies o-, m- and p-positions. That is, 1-phenyl-1-(o-isopropylphenyl)ethane, 1-phenyl-1-(m-isopropylphenyl)ethane, and 1-phenyl-1-(p-isopropylphenyl)ethane. Concerning the hydrocarbon solvent according to the present invention, it is most important that the content of the p-isomer of 1-phenyl-1-(p-isopropylphenyl)ethane in the whole solvent is 85% by weight or more. Both 1-phenyl-1-(o-isopropylphenyl)ethane and 1-phenyl-1-(m-isopropylphenyl)ethane are higher in viscosity than that of 1-phenyl-1-(p-isopropylphenyl)ethane, and their dissolving power for color formers used in pressure-sensitive copying material are smaller. Accordingly, if the content of 1-phenyl-1-(o-isopropylphenyl)ethane and 1-phenyl-1-(m-isopropylphenyl)ethane in the solvent exceeds 15% by weight, the properties as a pressure-sensitive copying material are unfavorably inferior to the hydrocarbon solvent of the present invention.
Furthermore, if the total amount of styrene dimers of 1,3-diphenylbutene and 1-methyl-3-phenylindane in the solvent is 5.0% by weight or more, the odor is too strong when it is used as a hydrocarbon solvent. This is unfavorable in the use for the preparation of pressure-sensitive copying material. Particularly, 1,3-diphenylbutene has a strong odor and produces disagreeable smell when it is mixed even in a trace amount.
Still further, if unsaturated hydrocarbons such as 1,3-diphenylbutene are mixed, it is apprehended that the heat stability and oxidation stability of the product of hydrocarbon solvent may be impaired. Therefore, it is preferable to avoid them from being get mixed as small as possible. In other words, in the solvent of the present invention, it is preferable to adjust the weight ratio of 1,3-diphenylbutene to 1-methyl-3-phenylindane to a level not higher than 0.02.
1-Phenyl-1-(isopropylphenyl)ethane can be produced by, for example, the well-known method described in Japanese Laid-Open Patent Publication No. 48-92114. However, with the conventionally known method, it is difficult to increase the content of isomer of 1-phenyl-1-(p-isopropylphenyl)ethane up to 85% by weight or more and to decrease simultaneously the content of styrene dimers of 1,3-diphenylbutene and 1-methyl-3-phenylindane in the whole composition to a level of 5% by weight or lower.
In the production of the solvent of the present invention, a solid acid catalyst having shape selectivity is suitable in order to react styrene with cumene. The catalyst is exemplified by crystalline zeolites such as Y-zeolite, ultra-stabilized Y-zeolite, mordenite, ZSM-5 and ZSM-12. By using these solid acid catalysts having shape selectivity, it is possible to suppress the formation of styrene dimers as by-products, especially 1-methyl-3-phenylindane.
The reaction is not limited so long as styrene and cumene are caused to react in a liquid phase. However, in order to produce the hydrocarbon solvent according to the present invention, the method as described in the following passage is preferable.
That is, a liquid mixture of styrene and cumene is fed into a two-stage reactor, in which the concentration of styrene in the starting materials is selected from the range of 0.5% to 70% by weight. By using a recycling method to circulate a part of the reaction product from a first reactor to the same reactor, the formation of 1,3-diphenylbutene and 1-methyl-3-phenylindane is suppressed as little as possible. The 1,3-diphenylbutene having strong odor in the reaction product from the first reactor is converted into 1-methyl-3-phenylindane by the reaction in a second reactor.
The preferable mode of the above two-stage reaction will be described more particularly.
The method comprises the following steps from (1) to (4) in order to add styrene to cumene.
Step (1): to bring cumene and styrene into contact with a solid acid catalyst in a liquid phase in a first flow-type fixed bed reactor so as to obtain a reaction mixture comprising unreacted components, cumene/styrene addition product, and unsaturated components,
Step (2): to circulate a part of the reaction mixture flowing out of the first reactor into the same reactor,
Step (3): to feed the remainder reaction mixture from the first reactor into a second reactor and bring it into contact with a solid acid catalyst in a liquid phase so as to decrease the unsaturated components in the reaction mixture, and
Step (4): to carry out distillation of the reaction mixture to obtain a fraction mainly consisting of cumene/styrene addition product and smaller contents of unsaturated components.
By the above method, it is possible to obtain cumene/styrene addition product containing smaller contents of unsaturated components, and to improve the yield of the above addition product.
In the following, the above steps will be described in more detail with reference to the attached drawing.
The attached drawing is a flow sheet indicating a process suitable for producing the hydrocarbon solvent according to the present invention. The main part of the reaction equipment in the drawing comprises a first reactor 1, which has a flow-type fixed bed that is packed with a solid acid catalyst; a circulation line 2, which returns a part of the reaction mixture from the first reactor back to the inlet of the same reactor; and a second reactor 3, which is packed with a solid acid catalyst. The symbol xe2x80x9c4xe2x80x9d denotes a distillation column in the separation/refining step, which can separate and recover reusable starting materials if they remain unreacted.
Starting materials of cumene and styrene are supplied from a storage tank (not shown) into a line 5 with a transferring pump (not shown) in the form of a mixture that is prepared previously. The mixture of starting materials is joined with a circulating flow in the circulation line 2, and it is then fed into the first reactor 1. It is possible to feed cumene and styrene to the first reactor 1 through any other line. A reaction solvent can be used, but it is usually preferable to use the starting material of cumene itself as a solvent for reaction.
Concerning the mixing ratio of styrene and cumene that is supplied to the reaction system through the line 5, the concentration of styrene relative to the total of both components can be selected from the range of 0.5 to 70% by weight, preferably 5 to 50% by weight. The above-mentioned total of both components does not include the circulating flow through the circulation line 2.
As the first reactor, a flow-type reactor with a fixed bed of solid acid catalyst is employed. In order to attain appropriate heating, it is also possible to use, for example, an apparatus for circulating a heat medium. The reactor may be either a single tube system or an appropriate multi-tube system.
As the catalyst for the fixed bed, a solid acid catalyst having shape selectivity is suitable as mentioned in the foregoing. It is exemplified by zeolites such as Y-zeolite, ultra-stabilized Y-zeolite, mordenite, ZSM-5 and ZSM-12.
The reaction temperature can be selected in the range from 40 to 300xc2x0 C.
Meanwhile, the reaction pressure can be so selected that the reaction system is in a liquid phase. For example, it can be usually selected in the range from 0.01 to 10 MPa.
The LHSV (liquid hourly space velocity) can be selected in the range from 0.1 to 200 hxe2x88x921 based on the flow rate of starting materials passing through the line 5.
In the first reactor, cumene and styrene are brought into contact with a solid acid catalyst in a liquid phase to produce a cumene/styrene addition product and unsaturated components as well. More particularly, the styrene is added to the cumene to produce 1-phenyl-1-(p-isopropylphenyl)ethane and unsaturated components are sinultaneously produced. These unsaturated components are mainly unsaturated styrene oligoiners, which include dimer to tetramer and the like. These unsaturated styrene oligomers have molecular weights and boiling points that are close to those of aromatic compound-styrene adducts. Therefore, they are liable to mix into the intended cumene/styrene addition product.
As described above, a reaction mixture comprising unreacted components of cumene and styrene, a cumene/styrene addition product and unsaturated components, flows out of the exit line of the first reactor.
According to the present invention, a part of the reaction mixture flowing out of the exit line of the first reactor is passed through the circulation line 2, and joined with starting materials through the line 5 and circulated to the first reactor 1 through a line 6. The circulating flow rate is preferably 1 to 99 parts by weight, more preferably 25 to 99 parts by weight relative to 100 parts by weight of the total flow rate of reaction mixture that is flowing out of the first reactor 1. The circulation can be carried out by an appropriate means for transferring such as a pump (not shown).
As described above, because the method to circulate a part of the reaction mixture is adopted in the first reactor, the concentration of styrene supplied through the line 5 can be maintained relatively high. As a result, the productivity is improved and the size reduction of equipment can be attained. On the other hand, although the concentration of styrene in the line 5 is high, the concentration of styrene in the first reactor can be maintained on a constant low level. Accordingly, the formation of unsaturated components can be suppressed in the first reactor.
Concerning the whole reaction mixture flowing out of the first reactor 1, the remaining part that is separated from the foregoing circulating flow is supplied to the second reactor 3 through a line 7 as shown in the figure. The supply is then brought into contact with a solid acid catalyst in a liquid phase. As shown in the figure, the product flowing out of the first reactor 1 may be supplied continuously to the second reactor 3. In another mode of operation, if necessary, the portion of remaining reaction mixture from the first reactor 1 is stored in a storage tank for reaction mixture (not shown) and after that, it may be supplied to the second reactor 3, this is called as block operation.
The main purpose of the provision of the second reactor 3 in the present invention comprises the following two points:
(1) By circulating a part of the product flowing out of the first reactor 1, the content of unreacted styrene in the reaction mixture from the first reactor increases. Thus, by bringing the reaction mixture into contact with the solid acid catalyst in a liquid phase in the second reactor 3, the unreacted styrene is caused to react again to advance the addition reaction. As a result, the yield of cumene/styrene addition product is improved as a whole.
(2) In the second reactor 3, unsaturated components produced in the first reactor 1, specifically unsaturated styrene oligomers, are alkylated into aromatic compounds or self-alkylated (cyclized) into products having benzene rings in molecules. In both alkylation and self-alkylation (cyclization) of cumene, unsaturated styrene oligomers are converted into saturated compounds having no unsaturated carbon-carbon double bond.
Therefore, by carrying out the reaction in the second reactor 3, the content of unsaturated components in the reaction mixture is decreased.
In the second reactor 3, the same catalyst as the one used in the foregoing first reactor 1, can be used. The catalyst is exemplified by crystalline zeolites having the function of what is called molecular sieve, such as Y-zeolite, ultra-stabilized Y-zeolite, mordenite, ZSM-5 and ZSM-12, synthetic or natural amorphous metal oxides such as clay and silica-alumina, and cation exchange resins such as cross-linked sulfonated polystyrene, e.g. Amberlyst (trade name: made by Rohm and Haas Co.) Among these catalysts, the solid acid catalysts substantially having no shape selectivity such as synthetic or natural amorphous metal oxides such as clay and silica-alumina, and cation exchange resins such as cross-linked sulfonated polystyrene are favorable, and the solid acid catalysts such as amorphous metal oxides are used more favorably.
The type of reaction in the second reactor 3 may be any of continuous and batch-wise, and any of stirring vessel and flow-type fixed bed may be used. A preferable one is a flow-type fixed bed like in the case of the above first reactor 1.
The reaction conditions can be selected from the same ranges as those in the first reactor 1. For example, the reaction temperature can be selected in the range from 40 to 300xc2x0 C. The reaction pressure is so selected that the reaction is in a liquid phase. It is usually possible to select the pressure in the rage from 0.01 to 10 MPa. When a flow-type fixed bed is used, the LHSV is selected in the rage from 0.1 to 200 hxe2x88x921 based on the flow rate of starting materials that is passing through the line 5.
In the figure, an example is shown wherein a flow-type fixed bed is adopted as the second reactor 3. The product flowing out of the second reactor 3 is sent to the distillation column 4 through a line 8. After the distillation, a fraction containing the intended cumene/styrene addition product is taken out through a line 9. According to the present invention, the fraction containing cumene/styrene addition product such as diarylalkane containing little quantity of unsaturated components can be obtained easily by industrial separating means such as distillation.
In order to separate this fraction, ordinary industrial conditions can be employed. Specifically, by using a packed tower filled with appropriate packing material, the distillation is carried out, for example, with the theoretical number of separation stage in the range of 2 to 200, the reflux ratio of 0.1 to 50 and the pressure of 1 to 100 kPa. In the distillation column 4, cumene supplied in excess and, if necessary, unreacted styrene is separated and recovered, joined with the materials in the line 5 through a line 10, if necessary, and a storage tank (not shown), and circulated to the first reactor 1 through the line 6. Furthermore, in order to recover these unreacted components, the distillation column 4 can be of a multi-column type of series or parallel arrangement.
The fraction containing cumene/styrene addition product taken out of the line 9 is not low in heat stability and in oxidation stability because it contains less quantity of unsaturated components. In addition, according to the above production method using cumene and styrene as starting materials, styrene dimers having strong odor, especially 1,3-diphenylbutene, can be restrained from being mixed in the product. As a result, the product can be obtained, which is useful as various industrial solvents such as solvents for dyestuffs used for preparing a pressure-sensitive copying paper.
The hydrocarbon solvents according to the present invention is used not only independently but also by mixing together with other auxiliary solvents such as kerosene fraction, isoparaffinic solvent, n-paraffinic solvent, naphthenic solvent and alkylbenzene.
When the hydrocarbon solvents according to the present invention are used for pressure-sensitive copying materials such as pressure-sensitive copying paper, the electron-accepting color developers are not especially limited. For example, there are bentonite, zinc oxide, titanium oxide, kaolin, clay, activated clay, acid clay, zeolite, talc, colloidal silica and so forth. Furthermore, there are high molecular weight materials such as phenol resins, and aromatic carboxylic acids or their metal salts such as zinc salicylate, which have been increasingly used in recent years.
The colorless or light-colored electron-donating color formers which produce colors upon contact with the above color developers are not especially limited when they are used for pressure-sensitive copying materials such as pressure-sensitive copying paper. They are exemplified by triarylmethane base color former, diphenylmethane base color former, xanthene base color former, thiazine base color former, spiropyran base color former and so forth.
The examples of specific compounds of these color formers are as follows. Triarylmethane base color formers are exemplified by 3,3-bis(p-dimethylamino-phenyl)-6-dimethylaminophthalide (Crystal Violet Lactone, hereinafter referred to as xe2x80x9cCVLxe2x80x9d, sometimes), 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-di-methylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethylamino-phenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-phenyl-indol-3-yl)phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3,3-bis( 1,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarba-zol-3-yl)-5-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)-5-dimethylaminophthalide, and 3-(p-dimethylaminophenyl)-3-( 1-methylpyrrol-2-yl)-6-dimethylaminophthalide.
Diphenylmethane base color formers are exemplified by 4,4xe2x80x2-bis(dimethylamino)benzhydrine benzyl ether, N-halophenyl leuco Auramine, and N-2,4,5-trichlorophenyl leuco Auramine.
Xanthene base color formers are exemplified by Rhodamine B-anilino-lactam, Rhodamine B-(p-nitroanilino)lactam, Rhodamine B-(p-chloroanilino)-lactam, 3-dimethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-7-chloro-6-methylfluoran, 3-diethylamino-7-(acetylmethylamino)-fluoran, 3-diethylamino-7-(dibenzylamino)fluoran, 3-diethylamino-7-(methyl-benzylamino)fluoran, 3-diethylamino-7-(chloroethylmethylamino)fluoran, and 3-diethylamino-7-(diethylamino)fluoran.
Thiazine base color formers are exemplified by benzoyl leuco methylene blue and p-nitrobenzyl leuco methylene blue.
Spiropyran base color formers are exemplified by 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3xe2x80x2-dichloro-spiro-dinaphtho-pyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxybenzo)-spiropyran, and 3-propyl-spiro-dibenzodipyran.
The above color formers are dissolved in a hydrocarbon solvent of the present invention for use, and the concentration of the solution is usually about 0.5 to 15% by weight.
Concerning the pressure-sensitive copying material according to the present invention such as the pressure-sensitive copying paper, a general production method will be described.
A solution containing the above color former dissolved in the present hydrocarbon solvent is emulsified in an aqueous solution of gelatin and gum arabic, and then gelatin membranes are formed around the emulsified oil particles by coacervation method to obtain microcapsules. Methods for forming resin membranes by interfacial polymerization or by in-situ polymerization are also widely used in recent years.
The thus obtained microcapsule emulsion of fine oil particles is applied to a sheet of paper, and a color developer is applied to the opposing surface of another sheet of paper or to the surface of the above emulsion coating in layers so as to prepare pressure-sensitive copying paper.
In the use of the pressure-sensitive copying paper, the microcapsules enclosing a dye solution are ruptured by the pressure of handwriting and the dye solution is brought into contact with the color developer to produce colors.
In another type one, the above microcapsule emulsion is applied to the surface of an ordinary sheet-like substrate material to form a pressure-sensitive copying material.